1 October 2012

I am 3 months pregnant. Should I monitor my weight? I don’t want to be left with ‘difficult-to-budge pounds after my baby is born. Well, not for too long! As a routine part of care, your obstetric care providers will keep an eye on your weight gain but most will steer away from discussing it for fear of causing your embarrassment or needless anxiety. Of course, women often discuss the subject among themselves, especially if it’s faster and greater than they expected. Many will tell you that even after the birth they retained a few kilos, and found them difficult to budge.

While their experience is common, we want to assure you that weight gain during pregnancy is under your control and, indeed, it’s good practice for you to monitor it yourself, so that you gain the ideal, or optimal, amount. OK, so what’s ideal? The optimal amount of weight gain over pregnancy is one that results in a ‘desirable pregnancy outcome’. That means a healthy baby, born at full term (about 40 weeks, or 9 months + 1 week gestation) with a birth weight of 3–4 kilograms or 6 to 9 pounds (I have rounded the conversions for easy reading) In women from affluent countries like Australia and New Zealand, who start pregnancy weighing between 60 and 65 kilograms (132 to 143 pounds), the average weight gain over pregnancy is about 13 kilograms (28 pounds) and the average infant birth weight is 3.4 kilograms (7½ pounds). But these are averages only. You’ll be pleased to hear that there’s a range of weight gains that are considered ideal. The desired amount depends to a large extent on your pre-pregnant weight. For a woman who is underweight, a higher weight gain is desirable, while an overweight mum should gain less.

US Institute of Medicine guidelines for pregnancy weight gain (2009)Your ideal total weight gain in kilogramsBMI less than 18.5 at the start of your pregnancy (underweight) – 13 to 18 kilos BMI 18.5–24.9 at the start of your pregnancy (normal weight) – 11 to 16 kilosBMI 25–29.9 at the start of your pregnancy (overweight) – 7 to 11 kilosBMI 30 or more at the start of your pregnancy (obese) – 5 to 9 kilos

Your ideal total weight gain in poundsBMI less than 18.5 at the start of your pregnancy (underweight) – 28 to 40 poundsBMI 18.5–24.9 at the start of your pregnancy (normal weight) – 25 to 35 poundsBMI 25–29.9 at the start of your pregnancy (overweight) – 15 to 25 poundsBMI 30 or more at the start of your pregnancy (obese) – 11 to 20 pounds

Weight gain in pregnancy is an excellent predictor of the baby’s weight at birth. This, in turn, predicts how well your baby copes in the first days and months of life. That’s the reason for the proud tradition of announcing not only the baby’s sex but its birth weight as well. Like many things in life, however, there is a happy medium. If you gain too little, it can mean a small baby who has been born too lean with little body fat. Small babies, defined as those born weighing less than 2.5 kilograms (about 5 pounds), have a higher chance of having poor outcomes during and after birth. Paradoxically, they are more likely to become overweight as adults and have a great risk of high blood pressure and heart disease. On the other hand, a baby that grows too big or too fast also has poor outcomes. Excessive weight gain during pregnancy and high birth weight (greater than 4 kilograms/9 pounds) are both linked to complications at birth, such as emergency Caesarean delivery, physical injury and post-partum haemorrhage. Just as importantly, excess weight gain also predicts the future health of both mother and baby.

This is an edited extract from my new book (with Dr Kate Marsh and Prof Robert Moses), The Bump to Baby Low GI Eating Plan for Conception, Pregnancy and Beyond (Hachette Australia). You can visit us HERE.

We are delighted to let GI News readers know that a US edition is on the way. The publisher is Matthew Lore of The Experiment. Matthew has published many of our books in the past and we are very happy to be working with him on this. We will keep you posted re publication details.